Vertical neutron beam focusing with bent mosaic crystals

6th European Conference on Neutron Scattering

Courtois, P.^1

Institut Max von Laue-Paul Langevin, 71 Avenue des Martyrs, CS 20156, Grenoble Cedex 9

38042, France^1

关键词: Defect concentrations;    Geometrical considerations;    High resolution diffractometers;    High temperature;    Neutron beam focusing;    Neutron monochromators;    Thermal neutrons;    Vertical focusing;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/746/1/012005/pdf
DOI  :  10.1088/1742-6596/746/1/012005

来源: IOP

【 摘 要 】

We report on the performance of bent mosaic crystals when used as a vertical focusing neutron monochromator. High-quality Cu(200) and Ge(335) mosaic crystals with a controlled curvature have been successfully produced at the ILL using plastic deformation at high temperature. As expected from simple geometrical considerations, they exhibit excellent properties for focusing a neutron beam vertically when examined on a high-resolution diffractometer installed on an m = 1 thermal neutron guide. Both Cu(200) and Ge(335) curved crystals allow a significant reduction of the focal image size at the sample position compared with a flat crystal with the same defect concentration. As a result, significant gain factors of 6 to 7 in intensity were obtained by replacing a flat crystal of 30 mm with a bent crystal.